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Getting started

Getting started#

The best way to get started with PyBADS is via the tutorials and worked examples. In particular, start with PyBADS Example 1: Basic usage and continue from there.

If you are already familiar with optimization problems and optimizers, you can find a summary usage below.

Summary usage#

The typical usage pipeline of PyBADS follows four steps:

  1. Define the target (or objective) function;

  2. Setup the problem configuration (optimization bounds, starting point, possible constraint violation function);

  3. Initialize and run the optimization;

  4. Examine and visualize the results.

Running the optimizer in step 3 only involves a couple of lines of code:

from pybads import BADS
# ...
bads = BADS(target, x0, lb, ub, plb, pub)
optimize_result = bads.optimize()

with input arguments:

  • target: the target function, it takes as input a vector and returns its function evaluation;

  • x0: the starting point of the optimization problem. If it is not given, the starting point is randomly drawn from the problems bounds;

  • lb and ub: hard lower and upper bounds for the optimization region (can be -inf and inf, or bounded);

  • plb and pub: plausible lower and upper bounds, that represent our best guess at bounding the region where the solution might lie;

  • non_box_cons (optional): a callable non-bound constraints function.

The outputs are:

  • optimize_result: an OptimizeResult which presents the most important information about the solution and the optimization problem. In particular:

    • "x": the minimum point found by the optimizer;

    • "fval": the value of the function at the given solution.

The optimize_result object contains more information about the optimization solution, see the OptimizeResult class documentation.

Additional data/parameters in the target function?

In case the target function requires additional data/parameters, they can be easily handled using an anonymous function. For example:

data = None # define your data
extra_params = None # define your function-specific parameters

def fun_for_pybads(x):
  return fun(x, data, extra_params)

# Pass fun_for_pybads to PyBADS

where fun is the function to optimize, note that fun_for_pybads only depends on x now, data and extra_params are given in the outer scope.

Examples & FAQ#

See the Examples for more detailed information. The Basic options may also be useful.

In addition, checkout the BADS FAQ page for practical recommendations, such as how to set lower_bounds and upper_bounds, and other practical insights. Even though the FAQ refers to the MATLAB version of BADS, most of the concepts still apply to PyBADS.

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